The present invention relates to a tensioner for wrapping connector driving members, such as belts and chains, and more particularly to a tensioner for giving specified tension, for example, to a timing belt reeved around a pulley on the crankshaft of a motor vehicle engine and a pulley on the camshaft thereof.
The timing belt is provided with a tensioner including an idler which is pressed against the belt as by the force of a spring to give a specified tensioning force to the belt by absorbing the stretch of the belt due to changes in the temperature of the engine or the elongation of the belt due to use.
Such belt tensioners heretofore known include one which comprises a pivot fixed to an engine or like fixed portion, and an arm rotatably supported on the pivot, having an idler rotatably mounted on its forward end and biased by a spring in a direction to press the idler against the belt (U.S. Pat. No. 4,601,683).
However, the conventional belt tensioner is relatively large-sized, requires a large space for installation and is cumbersome to handle because the idler is mounted on the forward end of the arm which is movable about the pivot.
Such belt tensioners are provided with a hydraulic damper for suppressing the resonance of the idler due to the vibration of the belt or of the engine. Nevertheless, the belt tensioner equipped with the hydraulic damper permits leakage of the oil, must therefore be replenished with oil and is cumbersome to maintain. Moreover, the hydraulic damper is complex in construction and expensive.